This invention relates to safety deck structure for vehicles more specifically, this invention relates to a safety deck structure which is mounted on the chassis members of a vehicle through the utilization of a novel and unique mounting structure.
Those familiar with vehicle construction and in particular the utilization of step and deck structure for truck-type vehicles recognize that the securing of said structure to the vehicle can present apparently minor but often difficult to resolve problems.
One generally recognized problem, and the problem to which the present invention is directed, is an acceptable method of mounting deck structure on the structural members of a vehicle either during original assembly of the vehicle or thereafter during modification or repairs.
The usual main structural or chassis members of a truck vehicle comprise a pair of parallel C-shaped channels which run from front to rear. Ordinarily the open side of the C-shaped members face inwardly. To these main structural members are secured and mounted the particular body of the vehicle, auxillary equipment such as gas tanks and the like and, often, deck grating or step structure to permit access of the driver or other person to the space immediately behind the cab or elsewhere as desired. The deck structure has been secured to the chassis either through the use of bolts or by welding. Although welding is a more permanent structural relationship and can be achieved where the metals of the chassis and the gratings are sufficiently similar to permit the welding, it is more difficult, and more expensive, and requires specialized welding equipment as will be recognized by those having skill in these arts. Further, welding any type of decks to truck chassis is undesirable because, inter alia, the chassis structure tends to anneal, welds crack as a result of vibration, and decks which are welded in place are not easily removable for maintenance.
Where the metals of the structures are so dissimilar as to preclude securing by welding and where it is not anticipated that welding equipment will be available, it has generally been recognized that bolting of the structural decks or steps is the desirable mode of securing.
Such bolting has been achieved in either of two ways; a hole is drilled in the structural member to accommodate the bolts, or a clamping type bolt such as a V-bolt has been utilized. Needless to say drilling holes in the structural members of the vehicle is an undesirable approach for the obvious reasons, i.e. it takes time to drill the holes and any holes, such as the bolt holes, tend to weaken the vehicle structure. Thus the operation is undesirable and not recommended by manufactures and unreasonably expensive.
The use of V-bolts has been found to be undesirable because of the particular structural configuration presented by the C-shaped channels. More specifically, based upon the size of the truck, the flange thickness of the structure member of the vehicle may vary from 1/4 to 3/4 of an inch. Where the flange thickness of the structural member is 1/8 of an inch the problem is not a major one because the flange element fits comfortably into the root of the V-bolt. Where, however, thicker structural flanges form the basis for supporting a deck structure, the thickness of the structural flange tends to create an opening moment on the clamping portion of the V-bolt. This opening moment experienced during both installation and operation, tends to cause the root portion of the bolt to be deformed and open thereby permitting the deck or step structure to become loose on the chassis. Obviously, such is not a desirable condition.
Approaches to solving this problem have for the most part been limited to providing V-bolts with a plurality of root dimensions in order to specifically accommodate the thickness of the particular flange dimension of the structural member of the chassis with respect to which the bolt is to be used. This of course requires an inventory of bolts, is thus expensive and often results in an incorrect bolt being utilized with respect to a particular structural member by reason of mechanic's error or the like.